Deducting Motorcycles

Two years ago, a man was offered a motorcycle for $1024, but he declined to buy it. A year later, he was offered the same motorcycle for $640, but again decided not to buy it. A little while after that, he was again offered the motorcycle, this time at $400. Again, he refused to buy it. Last week, he turned the motorcycle down even though the price had now fallen to $250. If the owner offers it for sale yet again, and he makes a consistent reduction, how much will it be for sale for the next time?

Comments

It easy to tell that the time intervals must be red herrings. Otherwise there would be no practical way to solve the puzzle. TROUBLE is it's unnatural that a year, a week, and other less determined periods all result in a 37.5% discount.